MOSSES WITH A HAND-LENS 



97 



It is hard to distinguish in a description between Mnium and 

 Bryum, but after one has collected them much he will rarely 

 make a mistake. In general the leaves in Bryum are smaller, 

 and the leaf cells are longer and proportionately narrower. The 

 Giant Bryum, however, is very like a Mnium in size and shape 

 of leaf. 



Many species other than those mentioned here are sure to be 

 found, but the genus is one of the most difficult, and cannot be 

 thoroughly studied with the hand-lens alone. Pohlia (Webera of 

 many authors) is treated with Bryum because of its close re- 

 semblance. It is by many authors included in Bryum. The leaf 

 cells in Pohlia are much longer and narrower than in Bryum, 

 but it is difficult to see this satisfactorily with a lens. 



B. ARGENTEUM L, v the Silvery Bryum, grows everywhere at 

 almost all altitudes. It is specially fond of dry compact soil in 

 sandy fields and waste places. It grows abundantly in paths and 

 between the bricks of sidewalks in towns and cities. 



When fully grown it is a bright silvery gray, due to the 

 fact that the leaves are white and without chlorophyll when old. 



The young plants are 



r\ WM tf^w**^ green and may easily be 



I A (Kf2 ff W N. mistaken for something 



W !M I m \ else - The leaves end in 



a slender bristle and are 

 crowded and closely 

 overlapping, making the 

 stems and branches 

 prettily julaceous. 



The capsules mature 

 in autumn, but can be 

 found in recognizable 

 condition at almost any 

 season. When fully 

 mature the seta and 

 capsules are dark red. 

 B. ROSEUM (Weis) Schreb, the Giant Bryum, is the largest 

 and showiest of all our species, and, moist and fully expanded, 

 is a striking object in any situation. The stems spring from 

 stolons and are nearly leafless except at the summit, where 

 the very large leaves form a rosette. Under favorable cir- 

 cumstances it forms large mats on old rotten logs or at the base of 



FIGURE 41. Bryum argenteum 

 branch X 10; capsule X 20. 



